Since 1982 over 2 million Afghan refugees have settled in the North West Frontier Province (NWFP) of Pakistan. Socio-economical factors, sudden urbanisation and psychological stress may influence the pattern of tuberculosis morbidity and infection among refugees as compared with the original population. In order to study the prevalence of tuberculous infection among Afghan children a tuberculin survey was carried out in April and May 1985 on a cluster sample of male children attending the first two grades of primary schools in refugee camps in the NWFP. The sample size was 4108 male children with an average age of 8 years. 1358 of them, average age of 7.8 years, had not been vaccinated with BCG. An infection prevalence of 13.8% was found when using a transverse diameter of 10 mm induration or more for the tuberculin test as the criterion for infection. The findings were compared with the results of a national sample survey carried out in Afghanistan in 1978: a downward trend of the annual risk of infection (ARI) of 7.8% per year was found in children of the same age group. Thus, Afghan children living in refugee camps in NWFP showed a lower ARI than was observed in their homeland 7 years earlier.